The present invention relates generally to an apparatus used in subterranean wells and, in some embodiments thereof, provides a retrievable annular safety valve system with a sealing element. Annular safety valves are used in various completion and/or workover assemblies such as those used in gas lift operations in subterranean wells. In a gas lift operation, gas, such as hydrocarbon gas, is flowed from the earth's surface to gas valves positioned near a producing formation intersected by a well. The gas valves are typically installed in production tubing extending to the earth's surface and permit the gas to flow from an annulus, between the production casing and production tubing, to the interior of the tubing. Once inside the tubing, the gas rises, due to its buoyancy, and carries fluid from the formation to the earth's surface along with it.
Because the gas is pumped from the earth's surface to the gas valves through the annulus, it is highly desirable, from a safety standpoint, to install a valve in the annulus. The valve is commonly known as an annular safety valve. Its function is to control the flow of fluids axially through the annulus and minimize the volume of gas contained in the annulus between the valve and surface. In most cases, the annular safety valve is designed to close when a failure or emergency has been detected.
One type of safety valve is a control line operated annular safety valve. Fluid pressure in a small tube (e.g., a control line) connected to the annular safety valve maintains the valve in its open position (permitting fluid flow axially through the annulus) against a biasing force exerted by a spring. If the fluid pressure is lost, for example if the control line is cut, the valve is closed by the spring biasing force. Thus, the annular safety valve fails closed.
In gas lift operations, the annular safety valve is typically positioned near the earth's surface such that, if a blowout, fire, etc. occurs, the annular safety valve may be closed. In this manner, the gas flowed into the annulus below the safety valve will not be permitted to flow upward through the annular safety valve to the earth's surface where it may further feed a fire.